"GTA IV is the fastest selling game ever on Play.com and has broken the record previously held by GTA San Andreas," Luzio told Next-Gen on Thursday.

He said that sales had been "neck and neck" between the Xbox 360 and PS3 versions of the game building up to release, but that in the last couple of days the 360 version had been "creeping ahead in daily sales". He did add that "the PS3 GTA IV hardware bundle sold out within 24 hours."

Both versions of the title are temporarily out of stock, but Luzio said that customers shouldn't have too long to wait before they can pick up a copy.

"We are receiving regular shipments from Take-Two and they have handled the biggest game release admirably. Congratulations to all of them for doing such a great job in difficult circumstances (enough groveling, give me more stock!)."

While business has been booming in recent weeks for UK videogame retailers, with the likes of Mario Kart Wii, Wii Fit and now GTA IV bringing in the pounds, Luzio said that the latter half of the year may yet prove to be even more rewarding.

"The platform holders have done a fantastic job in promoting gaming this year and I believe we are going to have an outstanding Christmas 2008 with games like Call of Duty 5, MotorStorm 2 and Gears of War 2 to name a few."

A spokesperson for UK-based Game, which opened 260 stores nationwide at midnight on Tuesday to accommodate demand for the game, told Next-Gen that it was finalizing new stock delivery details with Take-Two after virtually selling out of the title. "It's been a phenomenal launch," he said, but was unwilling to go into sales statistics.

On Wednesday ChartTrack revealed that GTA IV had broken UK opening day sales records after shifting 609,000 copies in its first 24 hours of availability. According to the sales monitor's estimates, the Xbox 360 version sold 335,000 copies on Tuesday, compared to 274,000 PS3 copies.